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# String Operations
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Text processing and manipulation functions for string columns in datatable.
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## Capabilities
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### String Functions
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```python { .api }
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def str.len(x):
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    """
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    String length function.
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    Parameters:
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    - x: String column expression
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    Returns:
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    Integer column with string lengths
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    """
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def str.slice(x, start, stop=None):
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    """
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    String slicing function.
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    Parameters:
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    - x: String column expression
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    - start: Starting index
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    - stop: Ending index (optional)
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    Returns:
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    String column with sliced strings
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    """
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def str.split_into_nhot(x):
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    """
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    Split strings into n-hot encoding.
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    Parameters:
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    - x: String column expression
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    Returns:
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    Frame with n-hot encoded columns
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    """
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```
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### Regular Expression Functions
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```python { .api }
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def re.match(x, pattern):
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    """
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    Regular expression matching.
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    Parameters:
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    - x: String column expression
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    - pattern: Regular expression pattern
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    Returns:
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    Boolean column indicating matches
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    """
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```
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## Examples
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```python
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import datatable as dt
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DT = dt.Frame({
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    'text': ['hello', 'world', 'datatable', 'python'],
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    'codes': ['ABC-123', 'DEF-456', 'GHI-789', 'JKL-012']
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})
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# String operations
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result = DT[:, dt.update(
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    text_length=dt.str.len(f.text),
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    first_3_chars=dt.str.slice(f.text, 0, 3),
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    last_2_chars=dt.str.slice(f.text, -2),
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    matches_pattern=dt.re.match(f.codes, r'[A-Z]{3}-\d{3}')
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)]
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```